1. Filed of the Invention
The invention relates to a process for the biological treatment of organic materials. The invention equally relates to an associated apparatus for carrying out the process.
2. Description of the Related Art
The waste industry has been subjected for some years to an accelerated restructuring process. In this process, the problem of disposal and utilization of biological wastes from households, commerce and industry is also increasingly assuming prominence. Numerous processes have been disclosed for biological, mechanical/biological or chemical/biological residual waste utilization. The best-known process used is composting animal and plant wastes, the organic substances being substantially degraded or converted by micro-organisms in an aerobic conversion process. In addition to the aerobic rotting process, anaerobic fermentation for treating biological wastes has also been disclosed, which likewise decomposes refuse with the action of microorganisms, with the exclusion of air. The two processes are used in waste technology either individually or in combination.
In particular during composting using an aerobic treatment, in a known preliminary rotting process, the material, to mix it, is continuously agitated in a rotting drum and is converted to fresh compost in a period of approximately one to two days. In the case of a static preliminary rotting, the material to be composted is at rest, and is aerated during this. This requires a considerable amount of space, in particular for the subsequent secondary rotting operation as well. The advantage of the dynamic preliminary rotting with continuous mixing of the refuse mixture is good aeration of the material, the occurrence of anaerobic points in the material being prevented.
The anaerobic treatment of organic refuse wastes or biowastes which has likewise been disclosed in recent years is based on an anaerobic fermentation, i.e. on a digestion process, which, with the exclusion of air, leads to biogas production in a weakly exothermic reaction. A process of this type has been disclosed, for example, by European Patent Document No. EP 0 037 612 B1, in which organic wastes are treated in a static process in a reactor with a leaching liquid which leaches soluble inorganic and/or organic materials from the material to be treated. This process takes place with the exclusion of air, i.e. under anaerobic conditions, as a so-called hydrolysis.
A disadvantage of this known process is, owing to the static disposition of the material, the formation of bypass flow channels, i.e. the applied liquid seeks the path of least resistance, via isolated channels, owing to a type of chimney effect, so that the material is only incompletely irrigated with washing liquid. The result is dead zones which are not leached, or are leached only insufficiently.